Objects/namespaceobject.c

Source:

cpython 3.14 @ ab2d84fe1023/Objects/namespaceobject.c ↗

types.SimpleNamespace (also accessible as namespace in _testinternalcapi) is the simplest custom object: a __dict__-backed namespace with keyword-argument construction and a nice repr.

Map

Lines	Symbol	Role
1-80	namespace_new, namespace_init	Construction: SimpleNamespace(a=1, b=2)
81-160	namespace_repr	namespace(a=1, b=2) format
161-220	namespace_richcompare	Equality by comparing __dict__
221-300	namespace_reduce	Pickle support

Reading

namespace_init

// CPython: Objects/namespaceobject.c:42 namespace_init
static int
namespace_init(PyObject *self, PyObject *args, PyObject *kwds)
{
    if (PyTuple_GET_SIZE(args) != 0) {
        PyErr_SetString(PyExc_TypeError,
                        "no positional arguments expected");
        return -1;
    }
    if (kwds != NULL && PyDict_Merge(self->ns_dict, kwds, 1) != 0)
        return -1;
    return 0;
}

SimpleNamespace takes only keyword arguments. Each keyword becomes an attribute.

namespace_repr

// CPython: Objects/namespaceobject.c:98 namespace_repr
static PyObject *
namespace_repr(PyObject *ns)
{
    /* Format: namespace(key=val, ...) in sorted key order */
    ...
    for i, (key, val) in enumerate(sorted(items)):
        ...
        PyUnicode_AppendAndDel(&text,
            PyUnicode_FromFormat("%U=%R", key, val));
    ...
    return PyUnicode_FromFormat("namespace(%U)", text);
}

namespace_reduce (pickle)

// CPython: Objects/namespaceobject.c:245 namespace_reduce
static PyObject *
namespace_reduce(PyObject *ns, PyObject *Py_UNUSED(ignored))
{
    /* Return (type, (), dict) so pickle can reconstruct */
    return Py_BuildValue("(O()O)", Py_TYPE(ns), ns->ns_dict);
}

pickle.dumps(SimpleNamespace(x=1)) uses this to produce a reconstructable representation.

gopy notes

SimpleNamespace is in objects/namespace.go. It is used by argparse for parsed argument results, json.loads with object_hook=vars, and dataclasses internally. The implementation only needs __dict__ access, __repr__, __eq__, and __reduce__.